Weigher head

ABSTRACT

A WEIGHER HEAD IS PROVIDED FOR USE IN HIGH SPEED, HIGH PRECISION ROTARY WEIGHTING MACHINES, IN WHICH HEAD A SYSTEM OF LEAF SPRINGS IS SUBSTITUTED FOR THE USUAL MEANS BY WHICH A SCALE BEAM WITHIN THE HOUSING OF THE HEAD IS PIVOTED. THE SPRINGS INCLUDE A PAIR WHICH ARE HORIZONTALLY DISPOSED, EACH BEING ANCHORED AT ONE END OF THE HOUSING AND AT THE OPPOSITE END THEREOF SECURED TO A VERTICALLY DISPOSED MEMBER BY WHICH A WEIGHING RECEPTACLE ASSOCIATED WITH THE HEAD IS SUPPORTED. THE LEAF SPRINGS FURTHER INCLUDE A VERTICALLY DISPOSED PAIR, ONE OF WHICH IS ANCHORED AT ONE END TO THE HOUSING, BEING SECURED AT ITS OPPOSITE END TO THE SCALE BEAM, AND THE OTHER OF WHICH IS SECURED AT ITS OPPOSITE ENDS TO THE BEAM AND TO THE RECEPTACLE SURRPORING MEMBER. THE HEAD ALSO INCLUDES FURTHER MEANS BY WHICH THE SCALE BEAM IS PERIODICALLY &#34;ZEROED&#34; TO COMPENSATE FOR THE DISTURBING EFFECT OF A POSSIBLE ACCERTION OF GREASE, COATING MATERIAL OR THE LIKE UPON THE WEIGHING RECEPTACLE, AS WELL AS TO COMPENSATE OUT OTHER FACTORS INFLUENCING HIGH-PRECISION WEIGHING.   PROVISION IS ALSO MADE TO MAKE ADJUSTMENTS FOR THE PURPOSE OF MAINTAINING PRECISE ACCURACY OF WEIGHING WITHIN PREDETERMINED HIGH AND LOW GOAL LIMITS.

Dec. 28, 1971 D. w. GARNI-:TT

WEIGHER HEAD Original Filed June 9, 1965 /A/l/.f/vrof;` DONALD w. GARN T@YW A TTORNEVS Unted States Patent Olhce Re. 27,263 Reissued Dec. 28,1971 27,263 WEIGHER HEAD Donald W. Garnett, Grand Ledge, Mich., assignorto The Olofsson Corporation, Lansing, Mich.

Original No. 3,369,620, dated Feb. 20, 1968, Ser. No. 462,674, .lune 9,1965. Application for reissue May 18, 1970, Ser. No. 48,754

Int. Cl. Glg 3/08 U.S. Cl. 177-229 16 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE A weigher head is provided for use in highspeed, high ,precision rotary Weighing machines, in which head a systemof leaf springs is substituted for the usual means by which a scale beamWithin the housing of the head is pivoted. The springs include a pairwhich are horizontally disposed, each being anchored at one end of thehousing and at the opposite end thereof secured to a vertically disposedymember by which a weighing receptacle associated with the head issupported. The leaf springs further include a vertically disposed pair,one of which is anchored at one end to the housing, being secured at itsopposite end to the scale beam, and the other of which is secured at itsopposite ends to the beam and to the receptacle supporting member, Thehead also includes further means by which the scale beam is periodicallyzeroed to compensate for the disturbing effect of a possible accertionof grease, coating material or the like upon the weighing receptacle, asWell as to compensate out other factors influencing high-precisionweighing. Provision is also made to make adjustments :for the purpose ofmaintaining precise accuracy of weighing Within predetermined high andlow goal limits.

The present invention relates to an improved weigher head of a type usedin multiple in weighing apparatus such as is the subject matter of mycopending application, Ser. No. 409,503, led November 6, 1964, nowLetters Patent No. 3,339,651 of September 5, 1967. That application inturn is directed to improvements in Weighing machines in accordance withLetters Patent No. 3,156,311 of November l0, 1964 to Olofsson andGarnett. More particularly, the present invention concerns a weigherhead having an improved floating mount for the scale beam which supportsfrom beneath a Weighing receptacle, to which discrete product ormaterial to be weighed is charged in an excess overweight, and thenvibrated to dribble feed or trim off the exact amount of the excessweight of material to bring the charge to an exact weight value.

The Letters Patent above identified have as their subject matter arotary type turret machine upon which a plurality of the weigher headsare arranged in a circumferential, horizontally traveling array. EarlierLetters Patent to Garnet and Olofsson, No. 3,094,182 of lune 18, 1963also have this type of weigher as their subject matter.

ln common with the majority of weigher heads for machines of the typereferred to above, the scale beam supporting the weighing receptacle,regardless of what type the latter might be, is very delicately balancedon horizontally aligned journal or bearing means, for examble, of a ballbearing or needle type. However, during an extended life of use inpractically continuous daily operation, such bearing provisions tend tobrinell, with consequent play or lost motion which is highly detractivein respect to desired accuracy. Moreover, the need for periodicinspection, servicing, maintenance or repair arises, representing timein which the weighing machine is non-productively down It is therefore ageneral object of the present invention to provide a weigher head havinga scale beam supporting a Weighing receptacle, this beam .being itselfsupported through the agency of floating mounting means which areentirely free of conventional mechanical pivots, bearings and journalcomponents.

More specifically, such beam balancing provisions comprise plural setsof elongated, flat leaf springs of substantial length, as well as widthin the transverse direction of a vertical plane in which they supportthe scale beam for floating action. The sets are herein shown in theform of a pair of parallel upright leaf springs and a set of threehorizontal and parallel leaf springs; and they afford the desiredfloating mount for the scale beam both in the horizontal direction ofits length and in the vertically transverse direction. Moreover, therelatively wide leaf springs, as fixedly clamped at opposite ends toanchoring components and to moving beam components, also afford adesired and necessary stability for the beam in the horizontal directiontransversely of its length.

However, it is contemplated that the exact number and disposition,position-wise, of the leaf springs of the respective sets may bealtered, so long as a universal floating mount of the scale beam in astably guided vertical plane can be had.

Still more specifically, it is an object of the invention to provide afloating scale beam mount for a Weigher head, in which the plural leafsprings employed for the purpose are fabricated in the form of laminatedfiberglass filaments of substantial length and horizontal widthtransversely of the plane just referred to; and in which an enclosed andsealed housing or casing for the scale beam is provided with integralformations or bosses to which ends of certain of the leaf springs arefixedly secured, certain other of the leaf springs having attachment atopposite ends thereof to beam components which they assist in floating.

More generally, it is an object of the invention to provide a weigherhead having a leaf Vspring-suspended scale beam as referred to above,the weigher head also incorporating certain automatic beam 'zeroingmeans and goal seeking and signaling means, ofuthe type shown anddescribed in my patent identified above, aswell as in the aboveidentified patent to Olofsson et al.

I am aware that it has heretofore been opposed to sustain weighingreceptacles of a rotary turret type machine by means of parallel leafsprings, lacking associated scale beam structure. However, with thesesprings naturally biased downwardly at their free ends by the weighingreceptacle and its load content, and otherwise unrestrained, the effectof centrifugal force in rotation is to straighten the leaf springstoward a true horizontal alignment, and to this extent to lessen theeffect of the true weight. However, the weigher head of the presentinvention, in coupling with a pair of horizontal and parllel leafsprings a further set or pair of vertical leaf :rings to afford aparallelogram type leaf spring struclre, provides vertical supportpreventing the disturbing fect of centrifugal force mentioned above.

Moreover, it has been found that weighers relying )lely on a pair ofleaf springs to sustain the weighing eceptacle are objectionablyresponsive to the effect of ibration of the weighing machine, as awhole, in operalon. That is, as the turret structure tends to vibrateertically, this effect is naturally transmitted to the inner lpportedends of the leaf springs, which naturally react 'ith opposite eifect attheir outer ends, thus in another :spect disturbing true weighingaccuracy. However, in weigher head such as the present, this disturbingvibra- )ry etfect is compensated out at the scale beam comonent thereof,with which leaf spring sets are associated 1 the manner described above.In other Words, the vertially downward force of the receptacle load atone end f the scale beam structure accompanies vertically down- Jardlyacting forces on fthe opposite end of the scale ea-m, i.e., oppositefrom the load to what would amount :u the fulcrum of a knife edge orbearing-pivoted beam, o that machine vibration has greatly reducedeifect on veighing accuracy.

The foregoing as well as other objects will become more apparent as thisdescription proceeds, especially vhen considered in connection with theaccompanying rawing illustrating the invention, wherein:

The figure is a view in side elevation and section in a ertical planejust inwardly of one of the side Walls of he housing of the weigherunit, i.e., looking horizontally oward the opposite side wall.

The improved weigher head of the invention is genrally designated byI'the reference numeral 10. It comrises an elongated rectangular, wellsealed box-like rousing or casing 11 of aluminum, within which a scaleearn structure (to be described) supports from beneath L vibratory trayor pan assembly generally designated y the reference numeral 12. Therewill be a plurality f such weigher head and vibratory units, for exampleifteen or more, supported in an annular array `by rotary able or turretmeans for continuous, motor-driven rotaive travel in a horizontal plane.The rotary supporting .tructure is intended to be of the typeillustrated and lescribed in the patents identified above.

Also associated with the weigher head are certain :omponents of a xedlymounted, electromagnetic scale )earn zeroing unit 14 and a further xedlymounted, goal veight seeking and adjusting unit 15. The unit 14 serves oinitiate a periodic compensation of the balance of a icale beam in head10 to offset error tending to arise rom certain disturbing effects;while the unit 15 serves o initiate signals reflecting chargesinsufficiently close in veight to a desired goal weight, all asdescribed in my atent No. 3,339,651. In any event, the actions of themits 14, 15, in eifecting periodic zeroing and goal weight tdjustmentson certain beam-biasing and beam-carried electrical switch components oflthe present unit 10, are :xactly the same in nature as in the case ofthe corre- ;ponding weigher heads of that application. Accordingly, :hepresent description will not 'be extended unduly in eference to thesesignaling and` adjusting actions.

In regard to the vibratory weigher receptacle assembly Jr unit 12, it,too, is similar to the corresponding unit )f my Patent No. 3,339,651,hence its features need be )ut briefly -referred to. It comprises anelongated tray or pan 17 extending radially of the rotative path of theweighing heads, and the weighed contents are vibratorily lribble fed-offor trimmed-off during the tray travel to aroper weight, then vibratorilydumped completely at a discharge station.

The pan 17 is supported by a known type of electromagnetic vibratorunit, generally designated 19, and the Jnit 19 is in turn supported bythe leaf spring balanced or floated scale beam structure of theinvention, as

4 mounted Within the housing 11 and generally designated by thereference numeral 21. The structure includes a front-to-rear elongatedbeam 22 having various provisions for Zeroing and for the initiation ofthe signals, as referred to above, which are hereinafter described.

Typically, Ithe vibratory unit 19 is shown as comprising a horizontaltop support 23 on which the pan or receptacle 17 is lixedly secured, thesupport 23 iixedly carrying on its bottom an electromagnetic armatureplate 24 of substantial size. A small air gap 25 exists between thearma-ture plate 24 and an electromagnet iield coil 26 directlytherebeneath, which is supported upon an inter mediate cross member 27of unit 19 paralleling its top support 23. In use coil 26 is energizedIby a rectied pulsatory voltage.

The upper and lower supporting members 23, 27, respectively, ofvibratory unit 19 are fxedly connected at their ends to one another bypairs of upwardly inclined, laminated fiberglass leaf springs 28, 29,with an upright rubber strap device 30 adjacent the forward pair tolimit vibratory throw of receptacle 17.

As thus springinterconnected, the supports 23, 27 are resilientlysecured by a pair of upwardly inclined front and rear isolation leafsprings 32, 33, respectively, to a bottom cross member 34 of thevibratory unit 19. This member is, in its turn, xedly secured at itsbottom to an upright stem member 36, with which the beam 22 isfloatingly associated as part of the scale beam structure 21. The stem36 extends downwardly through an opening 37 in the top wall of housing11, and is sealed about this opening, as by a exible diaphragm type ofseal 38, fixedly mounted by a clamp ring 39 to the housing, to prevententry of dust or foreign matter to lthe interior of the housing.

The weigher head housing 11, like those of my Patent No. 3,339,651,includes top and bottom walls 40, 41, respectively, in the former ofWhich the opening 37 is provided, side walls 42 and opposed, radiallyouter and inner, or front and rear, end walls 43, 44. The walls 40, 41and 43 are formed to provide certain integral internal projections orbosses providing anchors for some of the leaf spring type beam mountingor balancing members of the invention, as will be described. Thereceptacle supporting stem 36 extends downwardly almost to the bottom ofhousing wall 41, being formed to provide a pair of opposite siderecesses 45, 46 accommodating certain of the spring mounts.

Top housing wall 40 is provided adjacent its radially outer end wall 43with a thickened integral boss 47, at which a iirst horizontal leafspring 48 is secured 'by a screw 49, the spring 48 extending towards therear, where its opposite end is xedly connected to the stem member at50, as by a long upright screw extending from stem recess 45, whichscrew also secures an end of another leaf spring, to be described.

The end wall 43 of the housing is formed with a second integral boss 52at a somewhat elevated point thereon, the boss 52 serving as an anchorfor a further, rearwardly projecting horizontal leaf spring 53, and theopposite end of this spring is connected by a coil tension spring 54with an offset iinger or lug 55 on the bottom of stern 36, directlybeneath the recess 45 of that stem. Springs 53 and 54 function in theautomatic adjustment of bias on scale beam 22 during a zeroing phase inthe weighing cycle.

Stem offset -nger 55 also has the free end of a third horizontal leafspring 57 secured thereto as by a screw 58, and the opposite end ofspring 57 is anchored at the left to an integral boss formation 59 ofbottom housing wall 41.

Next an upright leaf spring 60 is xedly secured at its bottom end to theside of upright stem 36 opposite the latters linger 55; and a secondupright leaf spring 64 paralleling leaf spring 60 is lixedly anchored atits bottom to a bottom wall boss 65. The free upper ends of the leafsprings 60 and 64 are connected to a forward end of beam 22 of the scalebeam structure 21 by screws 65. Finally, this forward beam end iscoupled to the receptacle mounting stem component 36 of the scale beamstruc-ture, as by a leaf spring 66 connected to the stem by the screw50.

Actually, the spring 66 is primarily for the purpose of affordingstability to the beam and receptacle structure otherwise connected bythe sets of parallel arm leaf springs 48, 57 and 60, 64, both in thehorizontal transverse direction across the housing walls 42 and in thelongitudinal direction of beam 22; and, absent any need for suchstabilizing effect, the spring 66 may possibly be omitted.

As shown in the ligure, the intermediate horizontal spring 66 justreferred to is in horizontal alignment with the center of gravity beam22, as master balanced and counterbalanced in the manner to bedescribed, so that there is no tendency to set up a force moment onspring 66 under the centrifugal elfect.

A small hydraulic dash-pot unit 67 mounted on the bottom of housing 11has its plunger rod 68 -connected upwardly to the pin 62 on scale beamstem component 36 to stabilize the beam movement; and the plunger rod isbiased upwardly adjacent spring 60 by a small coil spring 61, which actsbetween a laterally extending pin 62 on the stem and an anchor pin 63fixed on the far housing wall 42. Thus lost motion at the plunger rodconnection is prevented, while allowing freedom of alignment of theplunger within the dash-pot. Similar dash-pot devices are shown in theGarnett Patent No. 3,339,651 and the Olofsson et al. patent mentionedabove.

Thus, it is seen that the set of three parallel and horizontal leafsprings 48, 57 and`66 coact with the set of two parallel upright leafsprings 60, 64 in providing a floatingly balanced mount for the scalebeam 22 which is sensitive with high accuracy to the changing weight ofthe vibratory receptacle unit or assembly 12, which is free of possiblelost motion or play, such as destroys needed accuracy inbearing-journalled beams as the result of brinelling, and which requiresno maintenance or other attention whatsoever following initial assembly.

Structurally, the leaf springs 48, 57, 60, 64 and 66 (and certain othersherein mentioned) are by preference constituted of a three-layerlaminate of epoxy-impregnated glass liber lilament material, in athickness of, say, 0.030, and in a transverse width slightly less thanthe horizontal spacing between side walls 42 of housing 11. Typically,this will be of the order of two inches.

To permit the intersecting relation of the horizontal stabilizing spring66 and the upright stabilizing springs 60, 64, the former is made in arectangular O-shaped outline and the latter are in a rectangularl-shaped outline, with the stems thereof received in the opening ofspring 66. T he transverse dimensions of the springs 60, 64 and 66 atthe ends thereof are equal and of the width mentioned above` Theimpregnated fiberglass material for the springs is dimensionally stable,not subject to atmospheric deformation or deterioration, or to a changedset in bias as the result of working or aging. As dimensioned in widthand thickness, the leaf springs 48, 57, 60, 64 and 66 provide a highlydesirable spring rate, as well as perfect lateral stabilization of thesweep of the scale beam structure 21 in a vertical plane.

The leaf spring 53 and coil spring 54, as has been indicated above, areemployed in an adjustment, durmg a zeroing phase of the Weightersrotative cycle, to comensate out changes in weight of the emptyreceptacle 17 such as result from an accumulation or accretion ofproduct coating on the walls of the receptacle, or occur as the resultof variations in spring tension or contact conductivity, etc., all asexplained in my patent identilied above. Means to adjust the bias ofspring 54 automatically in the zeroing phase are also the same, hencewill be but brieliy alluded to later.

The radially rearward or right-hand end of the scale beam 22 isappropriately counterpoised by weights 70 to balance beam 22 against theweight of the vibratory pan assembly 12; and an adjusting set screw 72is threaded into the beam for downward engagement with a horizontal,intermediate electrical contact 73 of brass leaf spring stock, the screwbeing appropriately insulated to transmit beam swing to contact 73.Actually, the contact means 73, appearing as a single contactor,represents two separate contacts arranged in parallel, side-by-siderelation to one another, these contacts being tixedly mounted at theirleft-hand end between laminae of an insulating mounting block 74, whichis lixed to and extends inwardly of the housing side wall 42.

The contactor means 73 is adapted to engage, in a check weighing phaseor phases in the weighing cycle, with pairs of upper and lower springbrass leaf contacts 76, 77 above and below the same, respectively. Hereagain, the contacts 76 and 77 are dual in nature, arranged in pairs inside-by-side relation to one another. Inasmuch as the provisions of thepresent invention do not extend to the electrical function of thecontact means 73, 76, 77, in which the present weigher head follows inall significant respects the circuitry of my Patent No. 3,339,651 (towhich reference may be had), it has not been deemed necessary to furtherillustrate the contacts or their wiring connections. Like theintermediate contact means, the respective contact means 76 and 77 arelixedly mounted in insulated relation to one another, and to means 73,by the mounting block 74.

The upper contact 76 is further shown as being sustained from above by arelatively less flexible, or even rigid, plate or strap 79 anchored atone end by mounting block 74, this strap adjustably carrying a small setscrew 80 which bears downwardly on the free end of contact 76; and anelongated leaf spring 81 of the glass liber stock is anchored at itsleft-hand end between the plate or strap 79 and the top lamination ofthe insulated block 74.

. Spring 81 has a clearance opening receiving the screw 80, whichadjustably backs the top contact 76; and the spring 81'extendssubstantially to the right beyond the last named contact for operationin 4response to the goal seeking and adjusting unit 15, in the samemanner as in my patent identified above, and as will be but brieliydescribed at a later point.

The right-hand or rear end of the scale beam 22 is shown as beinggenerally bifurcated in nature (between whose forks the insulatedmounting block 74 and its contact provisions are received). To this enda longitudinal plate 83 is suitably fixed to the bottom of the beam, theplate 83 fixedly mounting from above a block 84; and this block anchorsthe ends of a pair of upper and lower leaf springs 85, 86, respectively,also a motion limiting plate 87 beneath the spring 86. The springs 85,86 may be of the laminated and impregnated glass liber stock referred toabove, and they extend on either side of a stop pin 88 projecting fromthe housing side wall 42.

The function of the leaf springs just mentioned is to provide aresiliently cushioned, anti-bounce means to limit maximum swing of scalebeam 22, maximum motions of the ends of springs 85, 86 being in turnlimited from above and below by the rigid plates 83, 87, respectively.These provisions effectively damp out a possible and undesirablemechanical bounce back and forth of the scale beam in operation.

intermediate its length, the beam 22 is formed to provide a pair ofparallel, transversely spaced arm portions 90, 91, each provided with aV-shaped cleft 92; and a small transverse pin 93, upon which a number ofremovable weights 94 may be removably mounted, normally rests on thebottom of the aligned clefts 92. These weights, as described in mypatent, are selected to aggregate the weight of the intended product tobe weighed in pan 17 to an exact value.

As indicated above, the master weights 94 and the beam counterbalanceWeights 70 are so applied to scale earn 22 that the center of gravity ofthe latter, as thus 7eighed, is horizontally aligned with thestabilizing spring 6. Hence, there is no effect of setting up a momentarm n the spring 66 under centrifugal force. The line at which 1e latterintersects the left-hand upright stabilizing leaf pring 60 connectingstem 36 remains, in eect horizonilly stable, although the springs 60 and64 will assume a ery mild S-shaped outline in action.

Periodically, during a short zeroing phase in the rotave travel ofweigher unit 10, the weights 94 are adapted be raised from scale beam22; on the principle that, as ius relieved of a master counterpoise, thebeam Should be 1 exact balance, as between the weight of its vibratoryan assembly 12, including pan or receptacle 17 and ibratory unit 19, andthe main beam counterweight 70. Iowever, the accumulation of deposits onthe interior of eceptacle 17, or other changing electrical or mechanicallhenomena mentioned above, may prevent the balance, r otherwise disturba response to beam position.

For the purpose in question, a lifter bell crank, genrally designated96, is pivotally mounted at 97 on the ar side wall 42 of weigher headhousing 11. The bell rank includes lifter arm means 98 acting betweenthe ,rms 90, 91 of scale beam 22 and a tappet rod 99 dependng from thebell crank pivot externally of the far side rousing wall, it beingunderstood that the far arm 91 of earn 22 will be formed to provideclearance through vhich the pivot shaft of bell crank 96 may be receivedvithout interfering with the floating movement of the eam. The lifterarm 98 of bell crank 96 is provided with ts own small V-shaped cleft 100adjacent its free end, vhereby counterclockwise swing of the arm willengage he master weight-mounting pin 93 and lift the weights *4 out ofthe clefts 92 of the scale beam 22.

The bell crank 96 is urged in the opposite, clockwise lirection'by anupright leaf spring 101 anchored at its op in relation to lifter arm 98and engaging at its botom against a projecting piu 102 on housing sidewall 42. )epending substantially beneath the housing 11, the lower andof tappet rod 99 of the bell crank is adapted to periodcally engage afixed plate cam 103 to occasion the :ounterclockwise movement of lifterbell crank 96 against he bias of leaf spring 101. These matters aredetailed in ny Patent No. 3,339,651.

In order to permit access to the scale beam master veight unit 94 andother interior components associated herewith, the top wall 40 of thehousing 11 is provided Vith an elongated opening 105 of substantialsize, which s normally tightly closed and sealed by a cover plate 106,Vith an interposed sealing gasket 107, the plate being lorizontallypivoted at 108 and provided with a releasable :lamp 109 at its rear end.

As described in detail in my patent, the zeroing unit 14 :omprises ahorizontal plate 111 which is adapted to be shifted in one horizontaldirection by means of an elec- ;romagnet (not shown) and returned in theopposite lirection by a spring. An upright, reversely rotatable)perating stem 112 is suitably journaled ina tubular nount 113 dependingfrom the bottom housing wall 41. l`his stem is threaded at 114 in themount 113 and terninates in a reduced top extension 115 which bears fromJeneath on the leaf spring 53.

Stem 112 is provided beneath the mount 113 with a 'ubber tired frictionwheel 116; and this wheel is engageible, once per-rotative cycle ofweighter head 10, by one Jr the other of two upstanding pins 117 or 118carried )y the horizontal plate 111 of the zeroing unit 14.

The motion of pins 117, 118 is in response to an elec- :rical signal ata zeroing phase of the rotative cycle, just ifter the weighingreceptacle 17 has been dumped of its veighed product. In the event thereceptacle has increased n weight due to adhered product coating or thelike, the engagement of friction wheel 116 with one of the pins l17, 118will be such as to elevate stem 112 against the leaf spring 53, thusincreasing the lifting force exerted by coil spring 54 on the stem 36 toan extent to offset the weight of the adhered product; or to compensatefor variations in spring tension, contact conductivity and the like, allas mentioned in my patent.

Referring now to the goal weight signaling unit 15, it comprises a pairof electromagnet assemblies 120 and 121, respectively, carrying uprightpins 122 and 123. Otherwise, provisions of the unit 15 are similar tothose of the zeroing unit 14, so that corresponding components aredesignated by corresponding reference numerals primed.

As described in my patent, the signals initiated at both theelectromagnetic units 14, 15 are determined in part by the making andbreaking of the sets or pairs of contacts 73, 76 and 77; and theposition of the top Contact 76 is automatically adjusted by changing theupward force exerted by the stem extension on the non-conductive leafspring 81 which bears the set screw 80 backing the contact 76 fromabove. Inasmuch as in this respect, and in respect to the upward anddownward making and breaking of conducting contact with the pairs ofcontacts 76 and 77, respectively, the present weigher head 10 iselectrically identical, in the making and breaking of electricalcontacts, to the head described in detail in my patent, to whichreference may be made, it is not deemed necessary or desirable to burdenthe present description in connection with these features.

In use, motions of the beam 22 of scale beam structure 21 in response toa changing product weight on weighing pan 17 are delicately sustainedand guided by the set of three horizontal leaf springs 4S, 57 and 66,and the set of two upright leaf springs 60, 64. Rolling bearings arecompletely eliminated, together with their tendency to have play or lostmotion after a period of time. The epoxy impregnated glass fiber of thesprings in quetsion is inexpensive, yet operable under a long period oftime without change of flexure rate. Moreover, it is readily possible totune these springs at initial installation in the weigher head 10, as byan appropriate selection as to their thickness, length and width. Asindicated above, they are dimensionally stable under changingatmospheric conditions and throughout their life.

The action of the leaf spring sets 48, 57, 66 and 60, 64, respectively,is similar to that of a parallelogram motion, which, despite theflexible character of the parallelogram arms, is well stabilized, rst,by the `disposition of the upper and lower leaf springs 48, 57 withtheir connections to the stem 36 approximately equidisant from theintermediate horizontal spring 66 on opposite sides of the latter,secondly, the vertical stabilization of beam 22 afforded by the uprightleaf spring pair 60, 64 and, thirdly, by the substantial lateral widthof the several springs transversely of their length, to afford stabilityagainst horizontal shift transversely of the housing interior.

As explained above, the intermediate spring 66 also has transversestabilization effect on the floating beam structure, as well aslongitudinal eect.

In all, the accuracy of the combined scale beam structure 21 and theleaf spring provisions which connect it to the stem 36 supporting thevibratory pan unit 19 is insured against all disturbing effects found toarise in previous leaf spring type, rotary turret weighers. The beam 22,as it supports the load at parallel horizontal leaf springs 48, 57, isdisciplined by the spring pair 60, 64 against the normal tendency torise as the result of centrifugal force, hence is subject to nodisturbance of its weighing action from this effect.

By the same token, the combination of the leaf spring sets with amechanical scale beam 12, to which the downward force of the receptacleunit 19 and of the master weight and counterweight means 94, 97 areapplied, in effect, at opposite sides of what would normally representthe fulcrum knife edge of bearing of a mechanically pivoted beam, issuch as to be proof against loss of accuracy due to vibration of therotary structure of the weighing machine as a whole. This is to bedistinguished from the vulnerability of previous types of parallel leafspring-supported weigher units.

What I claim as my invention is:

1. A weigher head constituting one of a number of rotating heads of arotary weighing machine, said head comprising iiXed anchor means, aWeighing receptacle member, a beam member having means opeartivelyconnecting the same to said weighing receptacle member to support thelatter for movement in a vertical plane in the Weight-balancing of saidreceptacle member and its content, said means providing a floating mountof said receptacle and beam members for said movement and comprising apair of substantially parallel and horizontal leaf springs eachconnected at one end thereof to said xed anchor means and adjacent theopposite end thereof 'to said receptacle member, thereby affording aexible parallel arm suspension for said members, and at least onefurther leaf spring disposed at a substantial angle to the springs ofsaid pair, said further spring being connected to said xed anchor meansat one end and connected at its opposite end to one of said beam andreceptacle members to assist and stabilize said suspension, a masterweight normally carried by said beam member, and means operativelyconnected to said master weight to lift the latter from the beam memberin the rotation of the head on the machine.

2. The weigher head of claim 1, in which said further spring isconnected at said opposite end thereof to said beam member.

3. The weigher head of claim 1, in which there are a pair of saidfurther leaf springs in substantially parallel relation to one another,the second spring of said further pair being connected adjacent itsOpposite ends to said bea-m and receptacle members.

4. The weigher head of claim 1, in which said leaf springs are ofimpregnated glass fiber stock.

5. A Weighter head constituting one of a number of rotating heads of arotary weighing machine, said head comprising fixed anchor means, aweighing receptacle member, a beam member having means operativelyconnecting the same to said weighing receptacle member to support thelatter for movement in a vertical plane in the Weight-balancing of saidreceptacle member and its content, said means providing a oating mountof said receptacle and beam members for said movement and comprising apair of substantially parallel and horizontal leaf springs eachconnected at one end thereof to said fixed anchor means and adjacent theopposite end thereof to said receptacle member, thereby alfording aflexible parallel arm suspension for said members, and at least onefurther leaf spring disposed at a substantial angle to the springs ofsaid pair, said further spring being connected at its opposite ends tosaid beam and receptacle members respectively to assist and stabilizesaid suspension, a master weight normally carried by said beam member,and means 'operatively connected to said master weight to lift thelatter from the beam member in the rotation of the head on the machine.

6. A weigher head constituting one of a number of rotating heads of arotary weighing machine, said head comprising a fixed anchor, a movablescale beam structure, said structure comprising a member supporting aweighing receptacle and a scale beam member having means connecting thesame to said supporting member for movement with the latter in avertical plane in the weight-balancing of said weighing receptacle andits content, said connecting means comprising a rst pair of parallel andhorizontal leaf springs each connected adjacent one end thereof to saidfixed anchor and adjacent the opposite end thereof to said supportingmember, and a further pair of parallel leaf springs disposedsubstantially normal to those of said first pair, one spring of whichfurther pair is connected adjacent its ends between said xed anchor andsaid beam member and the other spring 10 of which further pair isconnected adjacent its respective opposite ends to said beam andsupporting members, a master Weight normally carried by said beammember, and means operatively connected to said master weight to liftthe latter from the beam member in the rotation of the head on themachine.

7. The weigher head of claim 6, and additionally comprising a further,generally horizontal leaf spring disposed between the first namedsprings of said first pair and connected adjacent Yopposite ends thereofto said beam and supporting members.

8. A weigher head comprising a housing enclosing a movable scale beamstructure, said structure comprising a member supporting a weighingreceptacle externally of the housing, and a scale beam member havingmeans connecting the same to said supporting member for movement withthe beam member in a vertical plane in the weight-balancing of saidweighing receptacle and its content, said connecting means comprising aiirst set of substantially parallel leaf springs, at least one of whichis connected adjacent its opposite ends between said beam member `andsaid supporting member and another of which is connected adjacent itsopposite ends to said housing and beam member, and a further set ofsubstantially parallel leaf springs disposed at a substantial angle tosaid first set, [one] a first spring of said further set being connectedadjacent its opposite ends between said housing and supporting memberand [another] ai second spring of said further set being connectedadjacent its opposite ends to said beam and supporting members.

9. The weigher head of claim 8, and further comprising an adjusting leafspring connected at one end to said housing, and a coil spring connectedbetween said adjusting leaf spring and said supporting member to biasthe latter in one direction, said coil spring having means engageabletherewith to vary the bias thereof.

10. The weigher head of claim 8, in which the leaf springs of said setsare of impregnated plastic stock.

11. The weigher head of claim 8, in which the leaf springs of said setsare of impregnated plastic stock and are of a transverse width somewhatless than the internal width of said housing, thus stabilizing saidsuspension.

12. The weigher head of claim 8, in which said further set includes afurther leaf spring connected between its ends between said housing andsaid supporting [members] member, said [further] second leaf springbeing located intermediate of and in general parallelism with said[named] rst and further springs of the further set.

13. The Weigher head of claim 12, and further comprising an adjustingleaf spring connected at one end to said housing, and a coil springconnected between said adjusting leaf spring and said supporting memberto bias the latter in one direction.

14. The weigher head of claim 13, and further comprising automaticallyacting means to vary the bias eX- erted by said coil spring.

15. The weigher head of claim 13, in which the leaf springs of said setsare of impregnated plastic stock.

16. A weigher head comprising fixed anchor means, a Weighing receptaclemember, a beam member having means operatively connecting the same tosaid weighing receptacle member to support the latter for movement in avertical plane in the weight-balancing of said receptacle member and itscontent, said means providing a floating mount of said receptacle andbeam members for said movement and comprising a pair of substantiallyparallel and horizontal leaf springs each connected at one end thereofto said xed anchor means and adjacent the opposite end thereof to saidreceptacle member, thereby affording a flexible parallel arrn suspensionfor said members, and at least one further leaf spring disposed at asubstantial angle to the springs of said pair, said further spring beingconnected to said fixed anchor means at one end and connected at itsopposite end to said beam member to assist and stabilize saidsuspension, and a third 1 1 1 2 ubstantially horizontal leaf springdisposed between said 3,062,308 11/ 1962 Anderson et al. 177255 X air ofhorizontal leaf springs and connected adjacent its 3,148,742 9/ 1964Giulie 177-46 pposite ends to said beam and receptacle members. FOREIGNPATENTS References Cited 5 569,382 1/ 1959 Canada 177--255 The followingreferences, cited' by the Examiner, 'are RICHARD B WILKINSON, PrimaryExaminer )f record in the patented le of thls patent or the original QH. MILLER IR., Assistant Examiner Jatent.

UNITED STATES PATENTS lo UUS' CL X-R 2,741,450 4/1950 Thayer et a1177-118X 17750 170 3,026,954 3/1962 Appius 177-229X

